1. Technical Field
The invention relates to an article rotating assembly for rotating conveyed articles. More particularly, the invention relates to an apparatus and method for the in-line rotating of selected articles without contacting or bumping the articles.
2. Background Art
Article turner assemblies are well known for rotating conveyed articles, i.e., for rotating the articles a designated amount, usually 90°, as they are conveyed along a path. Article turner assembles have many applications in a variety of article handling applications. For instance, an article turner assembly often is used as part of a pattern former of a palletizer.
Known article rotating devices have operating and structural characteristics which make them undesirable for use with many products and packages. Present day high speed conveying operations make any slow down in movement along the line or any shut-down of the line caused by package or product deterioration unacceptable.
Some article turner assemblies require contact between the operative element of the article turner assembly and a front and/or side surface of the article to turn the article. Article turner assemblies of this type are called “bump” or “turnpost” turners. In this type of article turner assembly, the article is conveyed so that the front surface of the article contacts a vertically-extending stationary turnpost and spins about the turnpost to effect the desired 90° of article rotation. The article impacts the turnpost with substantial force when the article is conveyed at high speeds. In the usual case in which the article comprises a package containing goods, this impact may result in substantial abrasion or other marring of the package and may damage goods contained in the package.
U.S. Pat. No. 6,126,383 uses a diverting mechanism which shoves turned cases to the side at a very high rate of speed. This diverter causes impact and friction to the sides of each turned article, while requiring the bottom of the article to slide across the infeed conveyor. Damage to the contents of the package (e.g., loose glass bottles in a case) is possible, while some soft-sided loose packages (e.g. bundles of paper towels, or stacks of newspapers) may be damaged on the sides or bottoms. Loosely packaged articles may shingle and not shift over at the bottom, causing a faulty turn or no turn at all. This device also relies on guides at the discharge end of the rotating mechanism for squaring centering turned articles, which is another point of potential impact, frictional product damage, or product jams.
Many turners require a significant number of precise adjustments when changing over from one article size to another. Adjustment in conveyor angle, diverter position, horizontal and vertical conveyor position, and speed differential must all be made when products change. Since most users run a variety of different products (sometimes hourly changes) this tedious adjustment and fine-tuning process is not desirable. While settings can be written down and repeated to some extent each time a product is to be run, it is a very difficult trial and error process to initially get the settings correct. Automatic linear actuation devices can be utilized to reduce the manual input into article changeover, but this adds significant cost and complexity to the device.
Brewpack Ltd. of Surrey, England makes a twin mattop belt inline turner which utilizes two side-by-side modular plastic conveyor belts, commonly referred to as mattop belts. The device typically consists of a wide belt with a low friction material, and a higher friction narrow belt that runs parallel to the wide belt. Both belts run at constant, but different speeds, so that when an article is in contact with both belts, the article tends to rotate (however, not about its center of gravity or geometrical center.) Articles are fed onto the turner largely in contact with the wide low friction belt. The narrow high friction belt stays slightly below the level of the wide belt, if the article is to remain unturned. If the article is to be turned, then one or more actuators raise one or more sections of the narrow belt to provide the speed differential required for article rotation. Since most of the article must rest on the wide belt so it is transported in a stable manner when not turned, only one edge is in contact with the narrow high friction belt when the article is to be turned. This style of turner basically references both turned and non-turned articles to one side of the device (the side with the narrow belt.)
A large gap is required between turned/non-turned articles since the sections of narrow belt that raise and lower are relatively long (a turned article cannot be in this section at the same time a non-turned article is.) Articles do not turn about their geometrical centers or their centers of gravity. Articles are referenced to one side of the device upon their exit. This can have a negative impact on the operation of downstream equipment such as slat dividers or pattern forming conveyors. It is desirable to have product exit the turner on the centerline in many applications.
There are several designs for devices that employ the “lift and turn” method of selectively rotating articles. However this is a very slow process, and is not suitable for high-speed inline applications.
U.S. Pat. No. 3,580,379 describes an inline article rotating device that utilizes a “slat divider” method for rotating packages. This type of device is very difficult to accurately control and fine tune. Different article sizes may require different size platens and lane locations that make this an impractical device for use with multiple products.
There are several designs for article turners that consist of multiple parallel conveyors with fixed speed differentials where all articles that pass through the device are rotated.